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Tension-Compression yield Asymmetry Influenced by the Variable Deformation Modes in Gradient Structure Mg Alloys

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Acta Metallurgica Sinica(English Letters) 2020年第2期33卷 252-266页

作者： Jiang-Li Ning Bo Xu Yun-Li Feng Xu-Dong Li Xin-Kang Li Wei-Ping Tong College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210China Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110004China

Surface mechanical attrition treatment(SMAT) was carried out on hot-rolled AZ31 Mg samples along two orthogonal directions;as a result,two types of gradient structures with different grain sizes and texture components in different layers were produced.The tension-compression yield asymmetry(YA) was studied using samples with different thicknesses,in order to elucidate the effect of combinations of variable deformation modes operating in different layers of the two oriented SMAT samples.The 0° oriented SMAT sample containing layers with strong basal texture displayed significant YA,because of either dislocation slip or extension twinning domination during tension or compression.By contrast,the 90° oriented SMAT sample containing layers with coexisting orthogonal texture components had an obviously weakened YA,which was attributed to the multi-deformation modes cooperating during tension or compression,i.e.,extension twinning or detwinning in conjunction with dislocation slips,leading to close yield stresses compared between tension and compression.

关键词： Mg alloy Gradient structure yield asymmetry Texture Deformation mechanism

Effects of mixed rare earth fertilizer on yield and nutrient quality of leafy vegetables during different seasons

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Journal of Rare Earths 2016年第6期34卷 638-643页

作者：任艳军任学军马建军闫立英 Analysis and Testing Centre Hebei Normal University of Science and Technology

Using Chinese cabbage and rape as test material and examining the same soil conditions at different seasons（spring and autumn）, the effects of mixed rare earth fertilizer on the yield and nutrient quality of leafy vegetables were studied to provide a theoretical basis for the application of mixed rare earth fertilizer in agriculture. Results showed a seasonal difference in the nutrient quality of Chinese cabbage and rape. For crops planted in autumn, the soluble sugar and vitamin C content were higher, the titratable acid and nitrate content were lower, and the sugar acid ratio was higher relative to crops planted in spring. Mixed rare earth treatments promoted growth of both crops during both seasons. The plot yield, stem and leaf fresh and dry matter weight, and dry and fresh ratio increased. These increases for Chinese cabbage were greater in autumn than in spring while for rape, the increases were greater in spring than autumn. The soluble sugar content, titratable acid content and sugar acid ratio were increased and the nitrate content decreased, in autumn the effects were more obvious than in spring. In spring, the vitamin C content was increased, and the increase was greater for Chinese cabbage than rape. In autumn, the vitamin C content decreased, and the decrease was greater for rape than Chinese cabbage. At the same time, the content of heavy metals such as Cu, Zn, Cd, Pb and Ni in stems and leaves decreased. This decrease was greater in spring for Chinese cabbage and in autumn for rape.

关键词： mixed rare earth fertilizer yield nutrient quality seasons Chinese cabbage rape

Estimating the average treatment effect of adopting stress tolerant variety on rice yield in China

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Journal of Integrative Agriculture 2018年第4期17卷 940-948页

作者： ZHOU Jie-hong TANG Li-qun Xiaohua Yu Center for Agricultural and Rural Development Zhejiang University Department of Agricultural Economics and Rural Development University of Goettingen

Climate extremes, characterized by droughts and floods, have become one of the major constraints to sustainable improvement of rice productivity. Variety choice, considered as one of the main adaptation measures, could help farmers reduce yield loss resulting from these extremes. Based on a three-year panel survey of 1 080 Chinese rice farms in major rice producing provinces, we assume Hicksian neutral technology and employ an IV regression to estimate the average treatment effect(ATE) on rice yield for adopting stress tolerant variety, and find that farmers who adopted the stress tolerant variety on average increased rice yield by 15.5% in comparison to the non-adopters.

关键词： climate extremes rice stress tolerant variety yield ATE endogeneity

Effect of Anisotropic yield Functions on the Accuracy of Material Flow and its Experimental Verification

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Acta Mechanica Solida Sinica 2019年第1期32卷 50-68页

作者： Bingtao Tang Yanshan Lou School of Mechanical and Automotive Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China School of Mechanical Engineering.Xi'an Jiaotong University Xi'an 710049China

This paper evaluates the performance of anisotropic yield functions based on mathematical methods which consider the prediction accuracy of yield stresses and values.The anisotropic yield functions being evaluated include one quadratic yield function and six nonquadratic ones.These yield functions are applied to describe the anisotropy of st eel sheets and aluminum alloy sheets to evaluate their predictability.The root-mean-square errors(RMSEs)are computed to quantitatively assess their performance.The computation results of RMSEs demonstrate that the Yld2004-18p yield function exhibits the highest accuracy but requires extensive tests to calculate anisotropic parameters.The Yld2000-2d and BBC2000 yield functions are the same and thus have the same prediction accuracy.The application to cylindrical cup drawing shows that,associated with the Yld2004-18p and Yld2000-2d yield functions,the finite element(FE)simulations of cup drawing process can predict cups with six or eight ears.Considering both efficiency and accuracy,the Yld2000-2d and BBC2000 yield functions,which have less anisotropic parameters to be calculated,are recommended for metals with intermediate anisotropy.

关键词： Anisotropic yield function Sheet metal forming Root-mean-square error

Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

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International Journal of Minerals,Metallurgy and Materials 2013年第6期20卷 574-581页

作者： Nil Baran Acarali Melek Bardakci Nurcan Tugrul Emek Moroydor Derun Sabriye Piskin Department of Chemical Engineering Y ld z Technical University

The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate （reference ZB） as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time （1-5 h）, reactant ratio （H3BO3/ZnO by mass： 2-5）, seed ratio （seed crystal/（H3BO3＋ZnO） by mass： 0-2wt%）, reaction temperature （50-120~C）, cooling temperature （10-80~C）, and stirring rate （400-700 r/min）; the modifying agents involve propylene glycol （PG, 0-6wt%）, kerosene （lwt%-6wt%）, and oleic acid （OA, lwt%-6wt%） with solvents （isopropyl alcohol （IPA）, ethanol, and methanol）. The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR）, and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.

关键词： zinc borate zinc oxide hydrophobicity yield

On the nature of a peculiar initial yield behavior in metastable β titanium alloy Ti-5Al-5Mo-5V-3Cr-0.5Fe with different initial microstructures

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Journal of Materials Science & Technology 2020年第3期38卷 135-147页

作者： Jiangkun Fan Zhixin Zhang Puyi Gao Ruimeng Yang Huan Li Bin Tang Hongchao Kou Yudong Zhang Claude Esling Jinshan Li State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an710072China National&Local Joint Engineering Research Center for Precision Thermoforming Technology of Advanced Metal Materials Xi’an710072China School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710129China Laboratoire d’étude des Microstructures et de Mécanique des Matériaux(LEM3) CNRS 7239Universitéde Lorraine57045MetzFrance Laboratory of Excellence on Design of Alloy Metals for low-mAss Structures(DAMAS) Universitéde Lorraine57045MetzFrance

The compressive yielding phenomenon of titanium alloys is not as focused and sufficiently ascertain as the tensile yielding phenomenon.In the present work,the peculiar compressive yielding behavior and the different dynamic responses of three different initial microstructures(singleβ,clavateβand lamellarβ)were investigated in an attractive metastableβtitanium alloy Ti-5553 using electron microscopes/crystallographic calculation/crystal plastic finite element simulation.Results reveal that the distinct compressive yielding behavior,steep peaks of sudden drop in the initial stage(very small true strain 0.03)of stress loading have appeared in the compression stress-strain curves except for the lamellarβinitial microstructure.Dislocation slip is the essential mechanism of the initial yielding behavior.Interlaced multiple-slip bands formed in the singleβinitial microstructure during the warm deformation process.A small quantity of single slip bands was observed in the deformed clavateβinitial microstructure.The abundant varied nano/ultrafineβsprecipitates were nucleated dynamically and dispersedly in all the three deformed initial microstructures.The multiple-slip bands formation and substantial nanoscaleβsresult in the highest peak of flow stress for singleβinitial microstructure.The compressive slip bands are formed early in the elastic–plastic deformation stage.As the increasing strain,the sample showed a significant compressive bulge,or eventually forming a strong adiabatic shear band or crack.These results are expected to provide a reference for the study of deformation behavior and mechanical properties of metastableβtitanium alloys.

关键词： Titanium alloy Initial yield Deformation mechanism Slip band Phase transformation Ti-5553

Equal perimeter yield criterion and its specific plastic work rate: Development, validation and application

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Journal of Central South University 2015年第11期22卷 4137-4145页

作者：章顺虎赵德文陈晓东 Shagang School of Iron and Steel Soochow University State Key Laboratory of Rolling and Automation (Northeastern University) School of Chemical and Environmental Engineering Soochow University

In order to overcome the nonlinearity of Mises criterion, a new linear yield criterion with a dodecagon shape of the same perimeter as Mises criterion was derived by means of geometrical analysis. Its specific plastic work rate expressed as a linear function of the yield stress, the maximum and minimum strains was also deduced and compared with that of Mises criterion. The physical meaning of the proposed yield criterion is that yielding of materials begins when the shear yield stress τs reaches the magnitude of 0.594σs. By introducing the Lode parameter, validation of evolution expressions of the proposed yield criterion with those based on Tresca, Mises and TSS criteria as well as available classical yield experimental results of various metals shows that the present results intersect with Mises results and coincide well with experimental data. Moreover, further application to the limit analysis of circle plate as an example is performed to demonstrate the effectiveness of the proposed yield criterion, and the subsequent comparison of limit loads with the Tresca analytical solutions and Mises numerical results shows that the present results are higher than the Tresca analytical results, and are in good agreement with the Mises numerical results.

关键词： EP yield criterion specific plastic work rate circ

A novel OPC method to reduce mask volume with yield-aware dissection

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Journal of Semiconductors 2013年第10期34卷 165-170页

作者：谢春蕾陈晔史峥 Institute of VLSI Design Zhejiang University

Growing data volume of masks tremendously increases manufacture cost. The cost increase is partially due to the complicated optical proximity corrections applied on mask design. In this paper, a yield-aware dissec- tion method is presented. Based on the recognition of yield related mask context, the dissection result provides sufficient degrees of freedom to keep fidelity on critical sites while still retaining the frugality of modified designs. Experiments show that the final mask volume using the new method is reduced to about 50% of the conventional method.

关键词： optical proximity correction dissection mask cost yield

Characterization and mapping of QTLs on chromosome 2D for grain size and yield traits using a mutant line induced by EMS in wheat

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The Crop Journal 2015年第2期3卷 135-144页

作者： Guizhi Zhang Yingying Wang Ying Guo Yan Zhao Fanmei Kong Sishen Li State Key Laboratory of Crop Biology/Shandong Key Laboratory of Crop Biology Shandong Agricultural University

Production of mutants with altered phenotypes is a powerful approach for determining the biological functions of genes in an organism. In this study, a high-grain-weight mutant line M8008 was identified from a library of mutants of the common wheat cultivar YN15 treated with ethylmethane sulfonate(EMS). F2 and F2:3generations produced from crosses of M8008 × YN15(MY) and M8008 × SJZ54(MS) were used for genetic analysis. There were significant differences between M8008 and YN15 in plant height(PH), spike length(SL),fertile spikelet number per spike(FSS), grain width(GW), grain length(GL), GL/GW ratio(GLW), and thousand-grain weight(TGW). Most simple correlation coefficients were significant for the investigated traits, suggesting that the correlative mutations occurred in M8008. Approximately 21% of simple sequence repeat(SSR) markers showed polymorphisms between M8008 and YN15, indicating that EMS can induce a large number of mutated loci. Twelve quantitative trait loci(QTLs) forming QTL clusters(one in MY and two in MS) were detected. The QTL clusters coinciding with(MY population) or near(MS population) the marker wmc41 were associated mainly with grain-size traits, among which the M8008 locus led to decreases in GW, factor form density(FFD), and TGW and to increases in GLW. The cluster in the wmc25–barc168 interval in the MS population was associated with yield traits, for which the M8008 locus led to decreased PH, spike number per plant(SN), and SL.

关键词： Common wheat Mutant Simple sequence repeat(SSR) Quantitative trait locus(QTL) Grain size trait yield trait